The present disclosure generally relates to waveguide joints, and more particularly, to a photonic choke joint structure for dual-polarization single-mode waveguides.
A waveguide joint is the location where two waveguides are connected or coupled to produce a reliable contact between two waveguide components, and typically provides an interface for a variety of modularized waveguide components. In general, two waveguides must be accurately aligned and have a low impedance electrical contact at the joint. Typically, this is done by having the two flat metallic waveguide flange surfaces make physical contact at the interface.
Ideally, a waveguide joint is lossless and reflectionless. In practice, it is sometimes necessary and/or desirable to realize this property with a non-contacting waveguide joint interface. For example, in some applications that require thermal isolation at the joint, the physical contact interface cannot be achieved. Without good electrical contact between two waveguide flanges, a few key problems arise. One problem is that the spacing between the mating or coupling surfaces of the two waveguides produces power leakage and reduces the efficiency of the joint. Another is that the spacing or gap between the two waveguides, also referred to as the flange interface, can produce spurious responses that interfere with the transmission in the waveguide. These spurious responses are highly dependent on the gap spacing and the shape of the waveguide. Finally, the gap also sets the limit in the waveguide breakdown voltage and its maximum operating power.
A half-wave choke structure at the flange interface requires good electrical contact and allows the joint to handle high power. One example of such a structure for a single-mode waveguide is the hexagonal tiling of metallic square pillars. The hexagonal tiling has been used for a standard 2.000:1 rectangular waveguide. However, this hexagonal tiling structure does not support dual polarization signal transmission. The half-wave choke structure also has a limited operating bandwidth and does not provide thermal isolation between the two waveguides. A hexagonal tiling photonic choke flange produces a broadband response and a low loss contact interface. However, the hexagonal tiling photonic choke flange structure does not have four-fold symmetry and produces spurious responses when this interface is used in a waveguide with dual polarization.
Accordingly, it would be desirable to provide a system that addresses at least some of the problems identified above.